Cyclodextrin-functionalized magnetic alginate microspheres for synchronous removal of lead and bisphenol a from contaminated soil

Currently, functional materials-based soil remediation focused on the stabilization of heavy metals and organics to inhibit their migration, however, the possible second release of these pollutants caused by soil condition variation attracts broad attention. Herein, beta-cyclodextrin functionalized magnetic sodium alginate microspheres (MSA-CDMW) were fast and facilely synthesized through microwave-assisted one-pot method for synchronous detachment of Pb and BPA from contaminated soil. The obtained MSA-CDMW presented wide pH adaptability and fast capture for Pb(II)/BPA with superior adsorption capacity of 369.03/165.37 mg/g. Furthermore, the effects of material dosage and soil pH on the remediation ability of MSA-CDMW were explored in detail. After adding 5% MSA-CDMW into the contaminated soil for 3-round successive remediation (12 h for each round), the amount of extractable Pb and total BPA was simultaneously decreased by 56.30 and 0.78 mg/kg, respectively. Meanwhile, the quantity of exchangeable and carbonate bound Pb was significantly decreased to 7.13% with transformation into relatively stable fractions. A series of characterizations revealed that ion exchange, pore filling, complex-ation, and electrostatic attraction were responsible for Pb binding, while MSA-CDMW could capture BPA through host-guest interaction by the hydrophobic cavity of beta-cyclodextrin. Additionally, recovery and floatation results revealed that the MSA-CDMW could be easily separated from the soil using magnets even at extreme drying and wetting conditions, thus providing a novel, fast, and eco-friendly strategy for effective remediation of heavy metals and organics contaminated soil.